No State Mandate In OK For Shelters; Joplin Thought About It Post-2011, But Too Expensive

[hatrack]

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But no local ordinance or building code requires such shelters, either in houses, schools or businesses, and only about 10 percent of homes in Moore have them.

Nor does the rest of Oklahoma, one of the states in the storm belt called Tornado Alley, require them — despite the annual onslaught of deadly and destructive twisters like the one on Monday, which killed at least 24 people, injured hundreds and eliminated entire neighborhoods.

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In 2011, a monster tornado razed large parts of Joplin, killing 160 people in a state that had no storm-shelter requirements. The city considered requiring shelters in rebuilt or new homes but decided that doing so would be “cost prohibitive” because the soil conditions make building basements expensive, said the assistant city manager, Sam Anselm. Even so, he estimated that half the homes that had been rebuilt included underground shelters. Schools were being rebuilt with safe rooms, he said.

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(Ed. - Moore's) Web site sounds tones that, in retrospect, might seem implausibly optimistic. It says the experience in 1999 — “an extremely unique event weatherwise” — meant that the standard “shelter in place” methods of protection were adequate. If another storm comes, “there’s only a less than 1 percent chance of it being as strong and violent as what we experienced” before.

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http://www.nytimes.com/2013/05/22/us/shelter-requirements-resisted-in-tornado-alley.html?_r=0

[AndyA]

1. Why Oklahoma doesn't have more basements/storm shelters

I checked to see why more basements and storm shelters aren't built in Oklahoma.

As far as basements go, parts of Oklahoma have bedrock not too many feet under the top layer of soil. In those areas, you'd literally have to use dynamite or a jackhammer to create room for a basement. This drives up construction costs considerably. Also, much of Oklahoma has clay soils which expand and contract depending on moisture content. During hot, dry summers the soil dries up and shrinks, no longer able to support foundations. This can cause severe settling making the structure unstable. When rain returns, the clay absorbs moisture and expands, but if this expansion isn't uniform, it can cause heaving of the structure in some areas, which can crack foundations causing structural deficiencies.

Piering can be utilized to help stabilize foundations, but parts of Oklahoma have water tables that can cause the ground to shift slightly, especially when combined with expansion/contraction soils. If the pier is installed where this shifting occurs, it too can cause foundation problems.

A lot of houses in Oklahoma, Texas, Missouri, and surrounding states have structural issues due to soil movement. Basically, our houses are built on a sponge. Too dry, it shrinks, too wet it expands and can't support the weight of the house. We have to "water the foundation" during periods of little rainfall to keep the ground around the house evenly moist to try to prevent damage--not too dry and not too wet.

Piering can be very expensive, easily running $20,000 or more depending on how many piers are needed. Sometimes, piering will correct problems, but at other times they require readjustments or simply don't hold as intended.

The above-ground safe rooms are less expensive, and provide about the same amount of protection, but can cost $10,000 to add to an existing home, and less in new construction.